[goal] Migrate testing to ubuntu focal

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

Fixing:
- bug#1886298
Bump the lower constraints for required deps which added python3.8
support in their later version.

- noqa for pep8 C901 check.

Closes-Bug: #1886298

Story: #2007865
Task: #40186

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-focal

Change-Id: I67b4957cea1ccbd5cdc0314d2eaddef0c24f7dfc

heatclient/v1/shell.py

@@ -740,7 +740,7 @@ def do_output_list(hc, args):
 @utils.arg('--with-detail', default=False, action="store_true",
            help=_('Enable detail information presented, like '
                   'key and description.'))
-def do_output_show(hc, args):
+def do_output_show(hc, args):  # noqa: C901
     """Show a specific stack output."""
     show_deprecated('heat output-show', 'openstack stack output show')
 

lower-constraints.txt

@@ -2,11 +2,11 @@ alabaster==0.7.10
 appdirs==1.3.0
 asn1crypto==0.23.0
 Babel==2.3.4
-cffi==1.7.0
+cffi==1.14.0
 cliff==2.8.0
 cmd2==0.8.0
 coverage==4.0
-cryptography==2.1
+cryptography==2.7
 debtcollector==1.2.0
 decorator==3.4.0
 deprecation==1.0
@@ -40,7 +40,7 @@ openstacksdk==0.11.2
 os-client-config==1.28.0
 os-service-types==1.2.0
 os-testr==1.0.0
-osc-lib==1.8.0
+osc-lib==1.14.0
 oslo.concurrency==3.25.0
 oslo.config==5.2.0
 oslo.context==2.19.2
@@ -71,7 +71,7 @@ python-openstackclient==3.12.0
 python-subunit==1.0.0
 python-swiftclient==3.2.0
 pytz==2013.6
-PyYAML==3.12
+PyYAML==3.13
 requests-mock==1.2.0
 requests==2.14.2
 requestsexceptions==1.2.0

requirements.txt

@@ -6,13 +6,13 @@ Babel!=2.4.0,>=2.3.4 # BSD
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 cliff!=2.9.0,>=2.8.0 # Apache-2.0
 iso8601>=0.1.11 # MIT
-osc-lib>=1.8.0 # Apache-2.0
+osc-lib>=1.14.0 # Apache-2.0
 PrettyTable<0.8,>=0.7.2 # BSD
 oslo.i18n>=3.15.3 # Apache-2.0
 oslo.serialization!=2.19.1,>=2.18.0 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 keystoneauth1>=3.4.0 # Apache-2.0
 python-swiftclient>=3.2.0 # Apache-2.0
-PyYAML>=3.12 # MIT
+PyYAML>=3.13 # MIT
 requests>=2.14.2 # Apache-2.0
 six>=1.10.0 # MIT